1. Field of the Invention
The present invention relates to a communication device, a communication system, a position detection method and a program.
2. Description of the Related Art
Various techniques have been proposed that detect a position of a device of its own or a device at the other end of communication with use of radio signals transmitted or received by radio communication. Among them, a technique that detects a position by using an array antenna is based on the prerequisite that signals arrive at a receiving array as spherical waves. It is thus necessary to lengthen a baseline of the receiving array according to an assumed distance to a signal source. However, if the antenna spacing of the receiving array is a half-wavelength or larger, a grating lobe occurs, which hampers determining a position uniquely.
In order to satisfy such conflicting conditions, U.S. Pat. No. 6,824,480, for example, discloses a technique that prepares a plurality of pairs of receiving antennas arranged with the spacing of a half-wavelength or smaller and widens the spacing between the respective pairs, thereby enhancing the accuracy of position detection.